It is planned to investigate the molecular mechanism of the alpha-adrenergic receptor in rat parotid gland membranes. For this purpose slices will be incubated with Pi32 to incorporate the label into cell membrane phospholipids. Redistribution of the label after incubation of isolated membranes with epinephrine will be analyzed by thin layer chromatography. The parotid acinar cell contains huge amounts of calcium in the secretory granules. Experiments are in progress attempting the depletion of the intact cells of most of the calcium. Studies of enzyme secretion in the depleted slices should answer the question whether the massive amounts of calcium are essential for enzyme secretion or that calcium serves mainly as a secretory product. BIBLIOGRAPHIC REFERENCES: Wallach, D., Kirshner, N. and Schramm, M. Non-parallel transport of membrane proteins and content proteins during assembly of the secretory granule in rat parotid gland, Biochim. Biophys. Acta 375, 87-105 (1975). Wallach, D., Tessler, R. and Schramm, M. The proteins of the content of the secretory granule of the rat parotid gland. Biochim. Biophys. Acta 382, 552-564 (1975).